1. Field of the Invention
This invention concerns a process for cospinning synthetic trilobal filaments having different trilobal modification ratios. More particularly, it concerns cospinning trilobal filaments from different spinneret orifice configurations.
2. Description of the Prior Art
Synthetic filaments having trilobal cross-sections and particular benefits associated therewith are described, for example, in U.S. Pat. Nos. 2,939,201 and 2,939,202. A characteristic of such filaments is their cross-section modification ratio, or MR. Certain benefits can be obtained from mixtures of such filaments or fibers having different modification ratios as described, for example, in U.S. Pat. No. 3,220,173. A convenient means of preparing such filament mixtures is to co-spin the different types in the desired ratio, and process the combined filaments through subsequent steps such as drawing, crimping, cutting into staple and so forth as a single, mixed-filament product. However, when filaments of two different modification ratios are co-spun from the same polymer, process adjustment to control the modification ratio of one filament independent of another is substantially impossible if the filaments are spun from the same type of spinneret orifice.
An object of this invention is to improve control over the modification ratio of filaments having different modification ratios under cospinning conditions from a common polymer supply.